If it is just a few fishes, you maybe able to shipping them as part of your luggage. You will have to check with the airport. If it is a business, it's totally different. Either way, US Customers Service still have to check the package before it can be released. So no contra-bands are allowed. They will just confiscate it and throw it away. If it is some kind of illegal fishes, they will arrest you on top of taking it away. You need to check with the US Customers Service before attempting to bring anything in this country. Also check with the Dept of Fish and Game for exotic fishes. If they are ornamental fishes such as goldfishes, you don't have anything to worry about. Good Luck.